EP2171147A2

EP2171147A2 - Method for controlling the generation of suds in a washing machine and a washing machine suitable therefor

Info

Publication number: EP2171147A2
Application number: EP08786004A
Authority: EP
Inventors: Harald MOSCHÜTZ
Original assignee: BSH Bosch und Siemens Hausgeraete GmbH
Current assignee: BSH Hausgeraete GmbH
Priority date: 2007-07-18
Filing date: 2008-07-09
Publication date: 2010-04-07
Anticipated expiration: 2028-07-09
Also published as: US20100192310A1; CN101755087A; CN101755087B; WO2009010432A2; DE102007033492A1; US8601625B2; EP2171147B1; PL2171147T3; WO2009010432A3; EA201070137A1; EA017272B1

Abstract

The invention relates to a method for controlling the generation of suds during the treatment of washing with suds consisting of an aqueous surfactant solution in a programme-controlled washing machine. Said machine comprises a solution drain system that is situated on the base of an outer tub (1), a solution pump, a rotating drum (2) and a heating unit (13). The method comprises the following steps: a) detecting the suds contained in the outer tub (1) and/or in the drum (2); and b) setting and/or maintaining a predefined range for the concentration of the suds between c1 and c2, the detection (a) of the suds being carried out by means of one or several sensors (15), which track a hydrostatic pressure p, a temporal gradient (Δp/Δt) of the hydrostatic pressure p and/or a conductance k in the outer tub (1) and/or in the drum (2). A measured hydrostatic pressure p is compared to a predetermined lower value p1 for the hydrostatic pressure and a predetermined upper value p2 for the hydrostatic pressure and if p<p1, the speed U of the drum (2) is increased and if p>p2, the speed U of the drum (2) is decreased. The invention also relates to a washing machine that is suitable for carrying out said method.

Description

Process for controlling foam production in a washing machine and washing machine suitable for this purpose

The invention relates to a method for controlling the generation of foam, in particular in a treatment of laundry with foam, in a program-controlled washing machine and a particularly suitable for carrying out this method washing machine.

In known washing process, the laundry to be washed only with an amount of water or wash liquor, also referred to as "liquor", treated, which is sufficient that the laundry to be washed is saturated with water and a minimum free liquor in the

Generally 2 to 3 liters, a mass transfer between the heating to heat the

Washing liquor and the laundry allows. The free fleet corresponds to the rest of the

Washing liquor that is not bound by the laundry and thus exists as a liquid. The appropriate dimensioning of the water quantity or liquor is ensured by suitable methods for regulating the water level in the drum and the adjustment of the amount of water to the suction capacity of the laundry. The free liquor results after deduction of the amount of water bound in the laundry of the filled into the washing machine

Amount of water. Cotton fabric binds about 200% of its own weight, so that a load of 6 kg of cotton fabric binds about 12 liters of water.

The energy consumption of a washing machine is essentially determined by the energy required for the heating of the water. A reduction in the amount of water in the washing machine would therefore be desirable, in particular a reduction in the amount of free liquor. However, the free fleet must ensure the heat transfer from the heater to the laundry. A reduction of the fleet and thus a reduction in energy consumption are thus difficult to achieve.

An alternative to this known washing process is the washing with foam, which can be produced by introducing mechanical energy into a wax liquor. The foam takes care of the heating and cleaning of laundry to be cleaned.

To a sufficient energy transport from a heater in one

To ensure washing machine in the laundry, a sufficient foam development is necessary. Due to the lower heat capacity of foam compared to the Heat capacity of a wash liquor would otherwise risk overheating the heater. However, if the foaming process is too strong, there is a risk of the foam escaping from the washing machine, in particular its dispenser tray. In addition, it should be noted that the development of foam depends on a large number of parameters. Some of the parameters can be influenced by a program-controlled washing machine by a corresponding design of the corresponding washing programs (for example, temperature, amount of water, speed of the drum). Type and amount of laundry and detergents (surfactants and other substances) and water hardness and degree of contamination of the laundry, however, are not influenced by a washing machine and are subject to unpredictable fluctuations from application to application.

In DE 43 34 969 A1 discloses a device for the destruction of detergent foam is described in a washing machine with a rotatable drum in a tub, which has a device for generating hot air, which is introduced through a supply line in the tub wall between the tub and the drum ,

According to the disclosure of DE 41 04 151 A1, foam which occurs undesirably in a washing machine is destroyed by switching on a heating device. In order to destroy the foam in the wider vicinity of the heater, the drum is rotated slowly so that more foam passes to the heater and is destroyed there by supplying heat.

In addition, methods for removing foam in a tub of a drum washing machine from DE 102 34 472 A1 and DE 198 46 248 A1 are known.

DE 102 34 472 A1 discloses a method for removing foam in a tub of an electronically controlled drum washing machine as a result of a program step, which is provided for dewatering of the tub, with a liquor drain system arranged at the bottom of the tub with a drain pump and a sensor for determining the height of the liquid in the tub. The course of the sensor signal (P) is recorded during the operation of the drain pump, contains a gradient Ap _n / .DELTA.t _n compared to Ap _n-1 / .DELTA.t _n-1, indicating the presence of foam, whereupon one of the Gradient-matched foam treatment measure is initiated. In EP 0 278 239 A1, excessive foam formation in the main wash, which can be observed during the heating of wash liquor in the tub, is eliminated by adding a limited amount of cold water and / or by temporarily switching off the liquor heating.

The object of the invention is to provide a method for controlling the generation of foam, in particular in a treatment of laundry with foam, in a program-controlled washing machine and a particularly suitable for performing this method washing machine.

According to the invention, these objects are achieved by a method having the features of patent claim 1 and by a washing machine having the features of patent claim 13. Advantageous embodiments of the invention are listed in the respective dependent claims. Preferred embodiments of the method correspond to preferred embodiments of the washing machine and vice versa, even if it is not indicated in detail in each case.

The invention thus relates to a method for controlling the generation of foam, in particular in a treatment of laundry with foam, from an aqueous wash liquor in a program-controlled washing machine with a liquor drain system arranged at the bottom of a tub with a drain pump, a rotating drum and a heater the method comprises the steps of a) detecting a foam present in the tub and / or in the drum, and b) adjusting and / or maintaining a range for the concentration of the foam specified by C ₁ to C ₂ , wherein detection (a) of the Foam by means of one or more sensors, the hydrostatic pressure p, a temporal gradient (.DELTA.p / .DELTA.t) of the hydrostatic pressure p, and / or a conductance k in the tub and / or in the drum follow, and wherein a measured hydrostatic pressure p with a predetermined lower value P ₁ for the hydrostatic Pressure and a given upper value p ₂ compared for the hydrostatic pressure and for the case

the speed U of the drum (2) increased, and in the case p> p _2, the speed U of the drum (2) is reduced.

The detection of foam can thus be carried out, for example, via a conductance measurement with two electrodes in the lower region of the tub.

In addition, a sensor used in any case in a known washing machine, referred to as a water level regulator, may, for example, be used as the sensor. In the measurement of the hydrostatic pressure is advantageous that a significant increase in pressure can be measured if, during rotation of the drum, in particular during spinning, a gap between the drum and the tub is completely filled with foam.

In the event that p> p ₂ , a1) the speed U of the drum (2) is preferably reduced by a predetermined speed difference ΔUi, a2) the pressure p is measured again after a predetermined period Δt and it is determined whether the relationship p < p _{2 is} met, and a3) for the case that p> p _{2 still} holds, the speed U is about ΔU _n (n is a natural

Number> 2), and steps a2) and a3) are repeated (n-1) times until a predefined value U _{mιn is} reached or undershot,

In the event that p <Pi, b1) the speed U of the drum (2) is preferably increased by a predetermined speed difference ΔUi, b2) after a predetermined period .DELTA.t the pressure p again measured and determined whether the relationship p ≥ pi is satisfied, and b3) in the event that p <Pi still applies, the rotational speed U is about ΔU _m (m is a natural

Number> 2), and steps b2) and b3) are repeated (m-1) times until a predetermined value U _{max is} reached or exceeded.

Here, m and n may be the same or different. In addition, the

Speed differences .DELTA.U _n and .DELTA.U _m are the same or different.

An increase in the speed of the drum causes more water or foam is ejected from the laundry. This increases the water level on a floor of the tub. As a result, enhancement of the interaction between this water and the rotating drum occurs. In addition, due to the greater speed of the drum more intense mechanical interaction also leads to an intensification of the development of foam.

On the other hand, a reduction in the rotational speed of the drum results in the undersaturated portion of the laundry, that is, in a laundry item having less water than it could bind to fully saturate the laundry with water at the instantaneous speed of the drum absorbed the laundry items and thus the amount of water in the gap between the drum and the tub is reduced. In addition, the reduced mechanical interaction reduces the generation of foam.

If, in the method _{according to} the invention, the rotational speed U has reached or _{fallen below} the predetermined value U _min , the rotation of the drum is preferably terminated a4); a5) water filled; a6) the drum is switched to a reversing operation, and / or a7) there is an indication that the detergent dosage is too high or incorrect.

If, in the method according to the invention, the rotational speed U has reached or exceeded the predetermined value U _max , the rotation of the drum is preferably terminated b4); b5) water filled; and / or b6) there is an indication that the detergent dosage is too low.

It is further preferred in the last two preferred embodiments that in step a5) or b5) water is introduced in an amount which allows a normal washing process with a wash liquor without foam and this washing process is carried out.

The display of too low (b6) or too high or incorrect detergent dosing (a7) is preferably carried out acoustically and / or optically. If, therefore, the desired area for the foam development can not be reached despite utilizing an available adjustment range for the rotational speed of the drum, then a signal can be output to a control device of the washing machine, which initiates further steps. If, for example, despite a maximum speed of the drum (also referred to as a "maximum spin speed"), it is not possible to generate sufficient foam, the washing process can be continued after the addition of water to the usual level as a conventional washing process An audible or visual signal may be issued about the lack of or insufficient detergent addition.

If, on the other hand, the foam development is so strong that, despite a minimum speed of the drum, the concentration of foam (also referred to as "foam level") is too high (eg if the user has added too much or a non-foam detergent for hand wash or for wool), Thus, the washing process can also be continued as a conventional washing process after addition of water to the usual level.At this, the user of the washing machine can be an audible or visual signal about the wrong or too high addition of detergent output.

After carrying out step a4) and / or a6) for a predetermined period of time, the inventive method can be carried out again.

Thus, for example, a strong turning of the drum (spin) can be switched off and switched over to a normal reversing operation of the drum for a predetermined time. As a result, the absorption of the water in the foam state is supported by the laundry items and thus effectively reduces the amount of foam. When reversing, a drain pump can also be switched on in order to reduce the amount of washing solution in the tub and available for generating foam. Following this lathering of the foam, an attempt can be made to switch back to spinning and, if a desired foam concentration is set, to carry out a foam-based washing process.

In carrying out the method according to the invention, the drum rotates, preferably at a speed U in the range of 200 to 600, preferably 230 to 500 revolutions per minute. Here, the lower limit is generally determined by the Resonance speed of the vibration system given and the upper limit by the maximum possible spin number.

During the process of the invention, the heater generally heats the foam and / or the wash liquor.

As an alternative or in addition to the methods already described, an evaluation of a desired / actual speed difference (U _so n -U | _St ) can be used to detect (a) the foam during a rotation of the drum. In the detection of foam on an evaluation of the target / actual speed difference, in particular during spin, use is made of the fact that the foam can brake a rotating drum, whereby there is a difference between the target and the actual speed , In this case, the association between a specific foam concentration and the target / actual difference is generally stored in a data memory of the drum washing machine.

A desired concentration c _{v of} the foam, which is predetermined in the range of Ci to C ₂ , can be adjusted and / or maintained by a continuous change in the rotational speed U of the drum.

The concentration C ₁ preferably corresponds to the hydrostatic pressure P ₁ and the concentration C _{2 to} the hydrostatic pressure p ₂ .

The invention also relates to a washing machine with a program control for controlling the program flow, a rotatably mounted in a tub drum, one at the bottom of the tub arranged Laugenablaufsystem with a drain pump, a drive motor for the drum, a heater, a sensor for determining a quantity of in the tub liquid or a foam, and switching means for rotating and stopping the drum, wherein the switching means and the sensor can perform the inventive method described herein.

When the foaming control method of the present invention has achieved the setting and maintenance of a desired concentration of foam, the treatment of a laundry load with foam can be performed. This can be achieved by a method for treating laundry with an aqueous wash liquor in a program-controlled washing machine with a liquor drain system arranged at the bottom of a tub with a drain pump, a heater, a sensor for determining the amount of a liquid in the tub or a foam, wherein a sensor signal is followed during the process, and a drum with a certain, relative to a loading amount of laundry comparatively small amount of water done.

The invention enables the stable operation of a washing machine in a foam using washing process. A desirable foaming is promoted while preventing foaming. The invention also ensures sufficient cooling of the heating device of a washing machine and can prevent the switching on of the heater when there is insufficient foaming.

An embodiment of a washing machine according to the invention for carrying out the method of the invention is shown in FIG. 1. Other embodiments are conceivable. The embodiment will be explained below.

Figure 1 is a schematic representation of the parts of a washing machine which are relevant for the explanation in which the described method can be carried out. The washing machine of the embodiment shown in Figure 1 comprises a tub 1, in which a drum 2 rotatably mounted and can be operated by a drive motor 14. In view of the ergonomics in dealing with such washing machines, the axis of rotation 3 of the drum 2 is directed from the horizontal by a small angle (e.g., 13 °) forwardly upwards, so as to provide easier access and insight into the interior of the drum 2. By this arrangement, in conjunction with specially shaped Wäschemitnehmern 4 and 5 Schöpfeinrichtungen for the wash liquor 6 on the inner surface of the drum shell also an intensification of the flooding of the laundry 7 with wash liquor and foam and a reduction of the free liquor is achieved.

The foam formed in a washing process with foam should in particular fill a space between the drum 2 and the tub 1. The washing machine has a liquor inlet system, which comprises a water connection fitting for the domestic water network 8, an electrically controllable valve 9 and a supply line 10 to the tub 1, which may optionally also be guided via a Waschmitteleinspüleinrichtung ("Einspülschale") 1 1, from which the feed water In addition, a heating device 13 is located in the tub 1. The valve 9 as well as the heating device 13 can be controlled by a control device ("program control") 12 as a function of a program flow chart. The control device 13 receives in particular the values measured by a sensor 15 for the hydrostatic pressure p in the tub 1, which are used to change or maintain a rotational speed of the drum 2. For this purpose, the drive motor 14 is controlled via the control device 12.

Claims

claims

A method for controlling foam generation, in particular in a treatment of laundry with foam, from an aqueous wash liquor in a program-controlled washing machine with a at the bottom of a tub

(1) arranged liquor drainage system with a drain pump, a rotating drum (2) and a heater (13), characterized by the steps a) detection of a in the tub (1) and / or in the drum (2) located

Foaming, and b) adjusting and / or maintaining a foam concentration range specified by C ₁ to C ₂ , wherein the detection (a) of the foam is effected by means of one or more sensors (15) having a hydrostatic pressure p, a temporal Gradients (Δp / Δt) of the hydrostatic pressure p and / or a conductance k in the tub (1) and / or in the drum (2) and a measured hydrostatic pressure p with a predetermined lower value P ₁ for the hydrostatic pressure and a predetermined upper value p ₂ for the hydrostatic pressure is compared and in the case the speed U of the drum (2) is increased, and for the case p> p _2, the speed U of the drum (2) is reduced.

2. The method according to claim 1, characterized in that for the case p> p ₂ a1) the speed U of the drum (2) is reduced by a predetermined speed difference .DELTA.Ui, a2) after a predetermined period .DELTA.t the pressure p again measured and found if the relationship p <p _{2 is} satisfied, and a3) in the case that p> p _{2 still} holds, the rotational speed U is reduced by ΔUn (n is a natural number> 2), and the steps a2) and a3) (n-1) times repeated until a predetermined value U _min reaches or _falls below, and in the case

P <Pi b1) the speed U of the drum (2) is increased by a predetermined speed difference ΔUi, b2) after a predetermined period Δt the pressure p is measured again and it is determined whether the relation p ≥ pi is satisfied, and b3) in the case that p <Pi still applies, the rotational speed U is increased by ΔU _m (m is a natural number> 2), and steps b2) and b3) are repeated (m-1) times until a predetermined value U _max reached or exceeded.

3. The method according to claim 2, characterized in that in the event that the rotational speed U has reached or _{fallen below} the predetermined value U _mιn , a4) the rotation of the drum is terminated; a5) water is introduced; a6) the drum (2) is switched to a reversing operation, and / or a7) an indication is given that the detergent dosage is too high or incorrect.

4. The method according to claim 2, characterized in that in the event that the rotational speed U has reached or exceeded the predetermined value U _max , b4) the rotation of the drum is terminated; b5) filling with water; and / or b6) an indication is given that the detergent dosage is too low.

5. The method according to claim 3 or 4, characterized in that for the case a5) or b5) water is introduced in an amount that allows a normal washing process with a wash without foam and this washing process is performed.

6. The method according to claim 3 or 4, characterized in that the display is carried out in an acoustic and / or optical manner.

7. The method according to claim 3, characterized in that after performing step a4) and / or a6) for a predetermined period, the method according to any one of claims 1 to 4 is performed again.

8. The method according to any one of claims 1 to 7, characterized in that the drum (2) rotates at a speed U in the range of 200 to 600 revolutions per minute.

9. The method according to any one of claims 1 to 8, characterized in that the heating device (13) heats the foam and / or the wash liquor.

10. The method according to any one of claims 1 to 9, characterized in that an evaluation of a target / actual speed _difference (U _so n - U _ιst ) in a rotation of the drum (2) for detecting (a) of the foam is used.

11. The method according to any one of claims 1 to 10, characterized in that a concentration c _{v of} the foam in the range of Ci to C _{2 is} predetermined and adjusted by a continuous change in the rotational speed U of the drum (2) and / or maintained.

12. The method according to claim 1, characterized in that the concentration Ci C ₂ corresponds to the hydrostatic pressure P ₁ and the concentration of the hydrostatic pressure _P2.

13. Washing machine with a program control (12) for controlling the program sequence, a in a tub (1) rotatably mounted drum (2), at the bottom of the tub (1) arranged Laugenablaufsystem with a drain pump, a drive motor (14) for the drum a heating device (13), a sensor (15) for determining an amount of liquid or a foam in the tub (1), and switching means (9, 12, 14) for rotating and stopping the drum, characterized in that the switching means (9, 12, 14) and the sensor (15) are adapted to carry out a method for controlling foam generation, in particular in a treatment of laundry with foam, from an aqueous wash liquor in the washing machine, comprising

Steps a) Detection of a foam in the tub (1) and / or in the drum (2), and b) Setting and / or maintaining a predetermined range of the foam from Ci to C ₂ , wherein the detection (a) of the foam is effected by means of one or more sensors (15) having a hydrostatic pressure p, a time gradient (Δp / Δt) of the hydrostatic pressure p and / or a conductance k in the tub (1) and / or in the drum (2), and a measured hydrostatic pressure p is compared with a predetermined lower value P ₁ for the hydrostatic pressure and a predetermined upper value p ₂ for the hydrostatic pressure and in the case the rotational speed U of the drum (2) is increased, and for the case p> p _2, the rotational speed U of the drum (2) is lowered.